Hidradenoma papilliferum with a ductal carcinoma in situ component: case report and review of the literature.

Hidradenoma papilliferum (HP) is a benign cutaneous adnexal neoplasm occurring mainly in the anogenital region of adult women and has features analogous to intraductal papilloma of the breast. Malignant change in HP is extremely rare. Only a single case of ductal carcinoma in situ arising in HP has been previously reported. We present a new case of HP which, in addition to the typical appearance of HP, contained a focus of ductal carcinoma in situ that appeared as enlarged pleomorphic epithelial cells having a "blastic" appearance, exhibiting atypical mitotic figures and surrounded by myoepithelial cells. Molecular biological study identified human papillomavirus (HPV)-16, which, it may be argued, may have played a role in the development of the carcinoma.